This invention relates to a torque transmission device with an hydraulic assembly for variable speed control, and more particularly, to a torque transmission device for use in a car, truck and the like, for controlling the speed thereof.
A torque transmission device with an hydraulic assembly is well known in the prior art, such as an hydraulic variable speed control device described in Japanese Patent Publication No. 9665/57.
The known device comprises a transmission mechanism having a swash plate pump and a motor which includes the same construction as that of the pump and communicates with the pump by means of a closed fluid circuit, and a gear transmission mechanism adapted to regain back-up torque generated in the pump to a driven shaft, so as to transmit torque from a driving shaft to the driven shaft through two parallel routes, one of which includes the fluid circuit and the other of which includes no fluid circuit but instead utilizes said gear transmission mechanism.
However, the known device of Japanese Patent Publication No. 9665/57 involves some unavoidable problems. One of them is that the driving and driven shafts thereof should be arranged in parallel with each other because the device includes gear trains in the transmission mechanism, and the other is that the device is very complicated due to the above-mentioned reason. Furthermore, the known device does not include a direct connection between the driving and driven shafts or an over-drive operation as is generally used in motorization systems.